The invention generally relates to dynamoelectric devices (electric motors and generators) more particularly, to a cryogenic tempering process for increasing the efficiency and performance of both electric motors and generators. There are many types of dynamoelectric devices that can benefit by this cryogenic tempering process. Some of them are alternating current (AC), direct current (DC), brushless direct current (BLDC), split phase, shaded pole and brush type motors. By utilizing this cryogenic tempering process on a standard dynamoelectric device, the unit will be more efficient, run cooler and lower operation costs.
In the case of the electric motor, it will consume less electricity and produce more power than before and the generator will produce more electricity for the same amount of drive input. This efficiency increase produces several benefits. The first being that the national demand for electricity could be drastically reduced thus reducing the consumption rate of our natural resources and lessening our dependence on foreign energy. Another benefit would be that motors could be made smaller for the same power output. So less raw material would be consumed and applications where size or weight were a concern. It is believed that all types of dynamoelectric devices will respond to this cryogenic tempering process. Everything from small fractional horse power (F.H.P.) motors to large 25-10,000 horse power (H.P.) motors will see similar results. The cryogenic tempering process can be done on both completed motors as well as applied to new motor components during the production process before final assembly. The cost of the cryogenic process will be minimal compared to the energy savings over the life of the unit.
Tests show that a motor""s efficiency will be increased by approximately twenty five percent (25%) at the motors rated operating speed and torque. The cryogenic tempering process benefits the copper winding in the motor/generator most directly. It is believed that the cryogenic tempering process relieves the stress in the copper winding left by the winding D process around (eg.) the iron lamination. The winding process induces stress in the copper winding and reduces the efficiency of the dynamoelectric device. By utilizing this cryogenic tempering process on the wound copper component, it will stress relieve the copper after the winding process. Revealing evidence shows that cryogenic tempering process on the copper winding has the capability to handle an increase in current. The ability to handle the increased current also means that the dynamoelectric device will run cooler for the same speed and load. Since resistance rises in copper as the temperature rises, the cooler the motor runs the more efficient the motor will be. So with the combination of running cooler, capable of moving electron flow more efficiently and the unit producing more performance, these three factors combine to equal a increase in efficiency of twenty five percent (25%) in the operation of the dynamoelectric device.
Tests were done to find which single segment of the motors construction responded to the cryogenic tempering process and was responsible for the increase in efficiency. The first test took a production fractional H.P. motor and testing for speed and torque and energy consumption. This test gave the base line for comparison. The same motor was then cryogenically tempered. The motor was then tested under the same test as before. When the before and after tests are compared, a 26.52% increase in efficiency was achieved. The motor was 25.6% efficient before the test and 32.39% efficient after the cryogenic tempering process. For comparison, untreated motors were tested and the findings recorded. Then some electrical components (but not rotor or stator) were treated by the cryogenic tempering process, and then these motors were re-tested and the findings recorded. After that other components like rotor and stator were treated by the cryogenic tempering process, which was followed by re-testing these motors again and the recording the findings again. The tests were indifferent until the stator with the copper windings were cryogenically tempered after being wound. The copper winding wire was treated before winding with no improvement in performance. So the tests show that the efficiency benefit to the motor is directly related to the motor""s copper winding being cryogenically tempered after being wound.
Because the cryogenic tempering process is permanent and the copper winding is stationary once wound, the copper retains the benefits of the cryogenic tempering process for the life of the dynamoelectric device.
In U.S. Pat. No. 5,442,929xe2x80x94Gillin, a cryogenic treatment of electrical contacts is disclosed in which, the contacts-under-treatment are enclosed within a sheath, such as a layer of aluminum foil, xe2x80x9cto cover the contacting surface and protect the contact from convection currents or other sources of thermal irregularities and to provide a uniform micro climate about the contact.xe2x80x9d U.S. Pat. No. 5,442,929.
U.S. Pat. No. 5,174,122xe2x80x94Levine, lists compound ways which cryogenic processing can go awry and diminish the wear ability of a part rather than extend it.
Some of the problems encountered with the prior apparatus described above arise as follows:xe2x80x94(1) delivery of liquid nitrogen to the bottom of the chamber below the payload platform often splashes or splatters the liquid on the payload parts causing extreme thermal shock to the parts that are still relatively warm, (2) the coldest gas in the chamber is just above the liquid and the gas does not flow upward (rise) to the payload parts-the cold gas does not reach the parts until just about all of the gas in the chamber is cold and the coldest gas will always be below the payload parts; (3) presoaking the part partially submersed in the liquid nitrogen causes the part to chill unevenly, as the portion of the part that is submersed chills much faster than the portion that is not submersed; and (4) any submersion of the part in the liquid nitrogen results in boiling heat transfer from the part at an excessive rate that does not allow all portions of the part to cool evenly. U.S. Pat. No. 5,174,122.
Certain formats of cryogenic treatment are known for extending the wear-ability of various steel alloy articles. For instance, the U.S. Patent to Nu-Bit, Inc., Pat. No. 5,259,200xe2x80x94Kamody discloses particular format of a cryogenic treatment for drill bits:xe2x80x94large drill bits, according to Kamody, the state of the prior art at the time of his invention practiced by the following convention:
As is apparent from the above description, the time period necessary to complete each step in the cycle of the treatment process generally is a minimum of about an hour per cross-section inch of the article being treated. Thus, for example, treatment of a steel article having a one inch cross-section in the minimum dimension would require a minimum of four hours total to complete the treatment according to generally accepted practices. In a like fashion, an article having a three inch minimum cross-section dimension would require a minimum of twelve hours total to complete the treatment according to the same accepted practices. However, it has been fairly conventional to increase the time periods for each step of the process to ensure that treatment is complete. Thus, for example, many of those practicing the above process routinely provide a safety factor of two or three or more in determining the respective time periods for the steps and as a consequence, overall treatment time periods of up to 50 hours or more for an article having a cross-sectional minimum dimension of one inch are often used. In using such extended time periods for the cryogenic treatment, it is believed that possible stress cracking and distortion of the article are thereby minimized or even eliminated. U.S. Pat. No. 5,259,200.
However, Kamody""s personal inventive efforts are directed at reducing such process time.
Generally, the commercial economics of metallurgical procedures dictate that a particular treatment should be accomplished as quickly as possible so as to minimize the size of the equipment necessary and thus equipment costs as well as requiring less space, energy and inventory in processing. Thus, for example, a tool steel article having a minimum cross-sectional dimension of about four inches, the maximum time for treatment [in accordance with Kamody""s discovery] of the article in the bath of cryogenic fluid would be about ten minutes. U.S. Pat. No. 5,259,200.
Another format of a cryogenic process for extending the wear ability of a steel articles disclosed by U.S. Pat. No. 5,865,913xe2x80x94Paulin et al., for firearm barrels. This patent for treatment of firearm barrels can be taken as representative of various others still. In general, cryogenic process is popular for steel alloys because it improves the resistance of metal to normal wear and tear. It is speculated that cryogenic processes affect the wear ability of steel by four known mechanisms:xe2x80x94conversion of austenite to martensite; precipitation hardening which may increase Rockwell hardness; formation of fine carbide particles; and residual stress relief. Whether the mechanics are truly known, actual trials on numerous articles bears witness to cryogenics efficacy. Thus, in the case of firearm barrels,
. . . the accuracy of a firearm is directly tied to the heat generated by repeated firing and the wear of the firearm barrel as the firearm barrels heat up from repeated firing they will wander off axis due to residual stresses in the metal structure. This movement though ever so slight when measured at the muzzle becomes quite significant when measured at a target 200-300 yards away. In addition as the firearm barrels wear, their ability to maintain accuracy is severely diminished. Frequent replacement of conventional firearm barrels and components is necessary, particularly in bench rest shooting, varmint hunting, shooting teams, and the military. Firearm barrels and components treated with the controlled thermal profiling process of this invention have demonstrated that they have reduced residual stresses and increased wear resistance. This allows the firearm barrels and components to be fired with greater accuracy for longer periods of time. U.S. Pat. No. 5,865,913.
However, cryogenic process is laced with problems in aspects of how to best carry it out. For example, from the above-quoted patent on the firearms barrelsxe2x80x94U.S. Pat. No. 5,865,913xe2x80x94it gave the warning that xe2x80x9csub-ambient treatments in the past utilized a liquid process which in some cases will cause thermal shock. This is detrimental as it will add stress to the structure.xe2x80x9d Id.
Accordingly, what is needed is an improvement as cryogenic process applied to dynamoelectric devices. A number of additional features and objects will be apparent in connection with the following discussion of preferred embodiments and examples.